Highly efficient conversion of sunflower stalk-hydrolysate to furfural by sunflower stalk residue-derived carbonaceous solid acid in deep eutectic solvent/organic solvent system

[Display omitted] •Furfural was produced in an aqueous choline chloride-maleic acid/toluene medium.•Tin-loaded sulfonated carbonaceous solid acid was prepared for furfural production.•82.6% of furfural yield was achieved using the carbonaceous solid acid catalyst.•Full utilization of biomass components for furfural production.•The catalytic reaction system has good reusability. Sunflower stalk was utilized as a source of raw material and catalyst for furfural production, and efficient conversion of xylose-rich hydrolysate into furfural was developed in an aqueous deep eutectic solvent/organic solvent medium by carbonaceous solid acid catalyst SO42−/SnO2-SSXR. The structural characteristics of SO42−/SnO2-SSXR was characterized by Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Fourier-transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Pyridine Adsorption Fourier-transform Infrared (Py-IR) and Raman. Under the optimum catalytic conditions, furfural (110.1 mM) yield reached 82.6% in a ChCl-MAA/toluene medium at 180 °C in 15 min by 3.6 wt% SO42−/SnO2-SSXR. Additionally, quite importantly, SO42−/SnO2-SSXR, ChCl-MAA and toluene had good recyclability for furfural production. The potential catalytic path of xylose dehydration into furfural was proposed by co-catalysis with SO42−/SnO2-SSXR and ChCl-MAA. This study revealed high potential sustainable application of furfural production.